Why was Purple chosen as the color of Royalty? Ask Our Readers More Questions

Q: Purple was once scarce and therefore it was known as the royal color.

Why was Purple chosen as the color of Royalty? Ask Our Readers More Questions

Q: Purple was once scarce and therefore it was known as the royal color. Why couldn't they just combine red and blue? Dan Warnock | Baker City, Oregon

Indigo and woad are two types of blue dyes that can be used to color fabrics. Madder is a red dye. The "Tyrian Purple" that is associated with royalty, which is believed to have been created in Phoenicia (modern Lebanon), around 1200 B.C., was made by extracting mucus form snails along the Mediterranean Sea. This labor-intensive and expensive process took a lot of time. This dye is praised for its bright hue and its color stability over time, according to ancient writings. These sea snails can be found all over the globe, and some cultures like the Mixtec weaver in Oaxaca (Mexico) still use them as dyes. --Jennifer Cohlman Bracchi is the head librarian at Cooper Hewitt Smithsonian Design Museum.

Q: Do you know of any invasive species that have helped improve the U.S. ecosystems' health? Frank Gregorio | Manassas, Virginia

The short answer to this question is no. Invasive species are species that pose a threat to the ecosystem. Many species are introduced accidentally and end up in gardens or containers. Non-native species can be introduced with good intentions, such as to prevent soil erosion and keep non-native plants under control. However, introducing non-native species to an ecosystem can lead to the possibility that they will outcompete or attack local species. It is best to avoid introducing them. --Gary Krupnick is the head of National Museum of Natural History's Plant Conservation Unit.

Q: How does the violin's body get its shape? Edwin Anderson | Glendora, California

Although bowed instruments have been around for over a thousand years, the earliest examples had just a few strings and were built with a narrow waist. By the 1400s instrument makers in Spain were making viola da gamabas with seven strings. The instruments had narrow waists to allow musicians to bow the top and bottom strings without hitting their sides. The first four-string violin was built by Andrea Amati of Cremona, Italy in 16th century. It is based on the design of the viola di gamba. His grandson, Nicolo, and his followers, including Antonio Stradivari, refined the violin family, which includes viola, cello, and violin. --Gary Sturm is the National Museum of American History's curator emeritus.

Q: Can a moth or butterfly's brain retain memories from its time as a caterpillar? Philip G. Grant | Pasadena, California

Once, we believed that metamorphosis was a process in which the caterpillar is completely disintegrated and its parts are rearranged. In a 2008 study, caterpillars were taught to associate the smell ethylacetate with mild electric shocks. The emerging adults had a similar reaction to the smell of the ethyl-acetate in the absence of shocks as the larvae. This suggests that some synaptic pathways were preserved. While adult moths or butterflies may not remember what it was like being a caterpillar, some associative memories can be retained into adulthood. --Floyd Shockley is the National Museum of Natural History's entomology collections Manager.

This article is a selection of the July/August issue Smithsonian magazine.